I have an Ampeg SVT-350 in the pawn shop that I owe about $200 bucks on and that includes a so-so GK backline 1x15 cab. Then I got to thinking..I don't mind the amp but these days I could do better. I see that Ampeg PF-500 heads are going for $249 used online. From what I hear the PF-500 has a good tone. I was a huge fan of the Ampeg B100R portaflex tone for rock music. How does the tone of the PF-500 compare? Also is it safe to buy these used one's from Guitar Center? I heard the earlier ones had reliability issues. I am thinking that what it would cost to get my SVT-350 and 1x15 out of pawn...I could just use that money and upgrade to something else. Opinions?